Fix a bug in tuple unpack.

The input may be reused in the Tuple_constuct node.
for example:
['input1', 'input1', 'input2']

nni/common/graph_utils.py

@@ -61,6 +61,7 @@ def __init__(self, model=None, dummy_input=None, traced_model=None):
             self.trace = traced_model
             # it's ok if the graph is already unpacked
             torch._C._jit_pass_inline(self.trace.graph)
+
         elif model is not None and dummy_input is not None:
             self.bound_model = model
             self._trace(model, dummy_input)
@@ -617,8 +618,9 @@ def unpack_manually(self):
                     errmsg = '%s Input number: %d if inconsistent with the output number %d' % (unpack_cpp, \
                         len(node.inputs), len(list(last_cpp.inputs())))
 
-                    assert len(node.inputs) == len(list(last_cpp.inputs())), errmsg
-                    for _debug_input, _debug_output in zip(node.inputs, node.outputs):
+                    in_debugnames = [x.debugName() for x in list(last_cpp.inputs())]
+                    assert len(in_debugnames) == len(node.outputs), errmsg
+                    for _debug_input, _debug_output in zip(in_debugnames, node.outputs):
                         # _debug_input = _input.debugName()
                         # _debug_output = _output.debugName()
                         if _debug_input in self.input_to_node and _debug_output in self.input_to_node:
@@ -629,7 +631,8 @@ def unpack_manually(self):
                             # will be merged into the same NodePyGroup, so we remove the `node` from
                             # input_to_node[_debug_input] and directly connect this tensor to the
                             # input_to_node[_debug_output]
-                            self.input_to_node[_debug_input].remove(node)
+                            if node in self.input_to_node:
+                                self.input_to_node[_debug_input].remove(node)
                             # add the following nodes of _output into the input_to_node[_debug_input]
                             self.input_to_node[_debug_input].extend(self.input_to_node[_debug_output])
                         # just remove the _debug_output from the grapgh index. So that we can also skip